Apparatus for movement of charge within an electric smelting furnace

ABSTRACT

An apparatus for moving the charge in an electric smelting furnace is disclosed. The apparatus comprises an annular member disposed within the confines of the furnace pot, said annular member having means for moving the charge towards the center of the pot when the annular member is oscillated or rotated.

United States Patent Krogsrud July 15, 1975 APPARATUS FOR MOVEMENT 0F [56] References Cited CHARGE WITHIN AN ELECTRIC UNITED STATES PATENTS SMELTING FURNACE 1.830992 11/1931 Frenzel 13/33 [75] Inventor: Harald Krogsrud, Gjettum, Norway 7 3/l956 Alexafldeh l3/33 2,794.843 6/1957 Sem et al.... 13/33 1 Asslgneer p g k t Oslo. $258,256 6/1966 Brooke 13 33 x Norway [22] Filed; Oct 22 1974 Primary Examiner-R. N. Envall, Jr.

Attorney, Agent, or FirmEyre, Mann & Lucas [211 Appl. No: 516,952

[57 ABSTRACT [30] Fure'gn Apphcamm Pnomy Dam An apparatus for moving the charge in an electric 23, 1973 Norway 4093/73 smelting furnace is disclosed. The apparatus comprises an annular member disposed within the confines of [52] the furnace POL said annular member having means Int. Cl. f r moving the harge towards the enter of the put Field of Search 13/1, 33; 2l4/21; 432/239,

when the annular member is oscillated 0r rotated.

7 Claims, 3 Drawing Figures APPARATUS FOR MOVEMENT OF CHARGE WITHIN AN ELECTRIC SMELTING FURNACE The present invention relates to electric smelting fur naces and more particularly to an apparatus for moving the charge in the electric furnace pot towards the center of the furnace where the electrodes are positioned.

It is well known in the smelting industry that it is de sirable to cause movement of the charge in the smelting furnace. This will help in reduction of formation of crusts and hangings in the furnace and will also result in a more even heat distribution. One known method of causing movement of the charge is to rotate the furnace pot. In conjunction with this there is also usually employed mechanical stoking or leveling ofthe charge surface. Rotation of the furnace pot has the special advantage that it results in more even wear of the furnace lining material.

A disadvantage to rotation of the furnace pot is that such procedure is limited to uncovered furnaces and further that secondary movement such as the beforementioned stoking or the like must also be employed.

It is also known that sinking of the charge will vary to a great degree across the furnace pot area. The consumption of charge is largest within the triangle formed by the electrodes and the consumption of charge decreases as the charge approaches the rim of the furnace pot. This uneven consumption of charge causes a number of disadvantageous conditions in the smelting process. the magnitude of which will vary depending upon the furnace type and the type of smelting product. For example. the concentration of dust will be comparatively very high in the areas where the consumption of Charge is smaller and this high concentration of dust will result in poor gas permeability which gives uneven heat distribution. This in turn causes poor prereduction of the solid charge in the furnace which results in the formation of crusts and hangings. Because of the collection of gas in these areas. explosions can result. Furthermore. the electrical resistance of the charge will vary considerably and the current from the electrodes can travel along unwanted paths. There is further the possibility of formation of false bottoms" and general clogging up of the furnace pot which will lead to incorrect submersion of the electrodes. Another potential problem is that the draining between the electrodes will be poor and the tapping conditions will be difficult.

In accordance with the present invention, these problems are substantially alleviated by the use of an apparatus which gives the charge an approximate horizontal movement in a direction towards the center of the furnace. i.e., towards the electrode triangle. Such apparatus is of use in both uncovered furnaces where it can replace mechanical stoking and in covered furnaces where it can effect movement of the charge. With the apparatus of the present invention the tendency for the furnace to encounter the disadvantages hereinbefore mentioned will be substantially reduced.

The apparatus of the present invention comprises an annular member which has a diameter smaller than the diameter of the furnace pot. The annular member is disposed within the furnace pot so that it can be rotated or oscillated. The axis of the annular member is preferably coaxial with the axis of the furnace pot. The annular member can be rotated as for example with tooth gear transmissions or can be oscillated as for example with hydraulic cylinders.

On the inner side of the annular member are provided means for effecting movement of the furnace charge. These means are preferably positioned so that they will exert a pressure against the charge which will cause the charge to move inwardly towards the center of the surface. The particular shape of the means for effecting movement of the charge is not critical but it is preferred that they be chordal segments of the annular member. It is. of course. appreciated that the height and width of these chordal segments in conjunction with the speed of rotation or oscillation of the annular member will directly affect the movement of the charge and in order to have variable movement of the charge. one or more and preferably each of these factors is made variable.

It is preferable that the annular member be of such size that an annular channel exists between the annular member and the furnace pot wall. In this manner. charge components can be supplied to the annular channel and thence move into the main furnace charge by movement of the annular member. This construc tion permits even distribution of the charge component by making it unnecessary to add it directly to the center of the charge where it might cause an over concentration while at the same time giving it movement from the furnace pot wall towards the center of the charge so that the charge component does not simply remain near the furnace pot wall where movement of the charge is normally at the lowest. Provision ofthis annu lar channel also permits the increased consumption of fines since means are provided for continuous movement of the fines towards the center of the charge thus eliminating poor gas permeability due to high concentrations of dust and the other disadvantages which re sult from poor gas permeability.

These and other aspects of the present invention may be more fully understood by reference to the drawings in which:

FIG. I is a vertical section through the middle of a smelting furnace including one embodiment of the charge moving means of the present invention;

FIG. 2 is a top view of the complete furnace of FIG. I; and

FIG. 3 shows a partial section ofa furnace according to the present invention with a plurality of charge moving members.

Referring now to FIGS. I and 2, there is shown a furnace pot 10 with lining I2 and electrodes 14 positioned in triangular relationship in the center thereof. A molten bath I6 has been established by supplying charge to the electrodes and the solid charge is 18. In accordance with the present invention, an annular member 20 is positioned within the furnace pot 10. The annular member has means for effecting movement of the solid charge towards the triangle of electrodes and in the drawing these are shown as chordal segments 22 of the annular member. The annular body is supported on the rim 24 of the furnace pot 10 by ball bearings 26 in engagement therewith affixed to supporting arms 28. Hydraulic cylinders 30 are also connected to supporting arms 28 to effect oscillatory movement of the annular member by push-pull" movement of the pistons 32 of the hydraulic cylinders. It will, of course, be understood that any suitable means can be employed to effeet rotatory and oscillatory movement of the annular member 20.

The particular configuration of members 22 is not limited to the chordal segments shown but should have a shape such that they will effect movement of the charge towards the center of the furnace pot. Naturally, the shape of the members 22 should be such that they do not place an unreasonably high torque on the annular member 20. Since the amount of torque which will be placed on the annular member will depend on the condition of the charge, the shape of the members 22 can be made adjustable either with respect to height or width so that the movement of the charge can be increased or decreased as desired. As mentioned hereinbefore, movement of the charge will also be affected by the speed of rotatory or oscillatory movement and this is also preferably made adjustable.

An annular channel 34 is preferably provided for receipt of charge components, fines and the like. The exact dimension of the annular channel is not critical but it should be large enough to receive the charge components or fines without their spilling over into the central portion 36 of the charge and the annular channel is preferably of uniform thickness throughout by making the annular member coaxial with the axis 38 of the furnace pot.

Member must be circular. It will also be understood that while a triangle of electrodes is certainly preferred, any other arrangement of electrodes can be employed if desired.

As shown in FIG. 3, it is also possible to employ a plurality of annular members 20 with means 22 for effecting movement of the charge. In such case, however, it is preferable that the horizontal force exerted by each annular member 20 have its effect below the lower rim of the ring to which it is adjacent on the inside of the furnace pot as shown in the drawing.

It will be understood that the claims are intended to cover all changes and modifications of the preferred embodiments of the invention, herein chosen for the purpose of illustration, which do not constitute departures from the spirit and scope of the invention.

What is claimed is:

1. In an electric smelting furnace having a furnace pot for containing a charge, the improvement comprising at least one annular member within the confines of the furnace pot, each said annular member being movable in annular direction and including means on the annular member effective to move the charge towards the center of the furnace pot when the annular member is moved in annular direction.

2. The apparatus of claim 1 wherein the movement in annular direction is rotation of the annular member.

3. The apparatus of claim 1 wherein the movement in annular direction is oscillation of the annular member.

4. The apparatus of claim 3 wherein the oscillation is effected by at least one hydraulic cylinder.

5. The apparatus of claim 1 wherein the means on the annular member effective to move the charge comprises members affixed to the annular member and of the shape of chordal segments of the annular member.

6. The apparatus of claim 1 wherein there are at least two annular members.

7. The apparatus of claim 6 wherein each annular member is effective to move the charge below the adjacent inner annular member. 

1. In an electric smelting furnace having a furnace pot for containing a charge, the improvement comprising at least one annular member within the confines of the furnace pot, each said annular member being movable in annular direction and including means on the annular member effective to move the charge towards the center of the furnace pot when the annular member is moved in annular direction.
 2. The apparatus of claim 1 wherein the movement in annular direction is rotation of the annular member.
 3. The apparatus of claim 1 wherein the movement in annular direction is oscillation of the annular member.
 4. The apparatus of claim 3 wherein the oscillation is effected by at least one hydraulic cylinder.
 5. The apparatus of claim 1 wherein the means on the annular member effective to move the charge comprises members affixed to the annular member and of the shape of chordal segments of the annular member.
 6. The apparatus of claim 1 wherein there are at least two annular members.
 7. The apparatus of claim 6 wherein each annular member is effective to move the charge below the adjacent inner annular member. 